First off, how badly does the parent company need you to be on their VMs? It's probably necessary work, but not important. Everyone will still have jobs if it doesn't finish for a couple quarters. In the meantime, let your boss know you're blocked, start tracking this as a dependency, and go work on something else.

In my experience, it helps a lot to imagine the motivations behind each process in an uncynical light. Everyone is trying to solve their own problems, which aren't necessarily the same as your problems or the organization's as a whole. You went from an environment where whatever you were working on was a huge part of the overall organization to another environment where, proportionately, it simply isn't as important. If your startup had kept going, it would've ended up looking very similar as it got bigger.

Large companies are just startups that've learned more hard lessons. Every one of those processes were put in place in order to protect something or someone from the harms of doing what you're doing. They didn't emerge from nothing. You don't have to like it, but I encourge you to respect it.